Automatic drill slip unit



W. A. ABEGG AUTOMATIC DRILL SLIP UNIT Nov. 20, 1951 2. SHEETS-SHEET l Filed Deo. 17, 194e mw hm uw S 1 mm \N QN /HI/E'NTOQ, hm T52 ,4. ,45566 ATTOQ/VEK W. A. ABEGG AUTOMATIC DRILL SLIP UNIT Nov.` 20, 1951 2 SHEETS-SHEET 2 Filed Deo. 17, 1946 /h/l/EP/Tlo/Q/7 /VALTEE ,4. ,45566 ATTOQ/YEK Patented Nov. 20, 1951 UNITED STATES PATENT OFFICE Walter A. Abegg, Los Angeles, Calif., assigner, by mcsne assignments, to Abegg & Reinhold C0., Los Angeles, Calif., a corporation of California Application December 17, 1946,'Serial No. 716,767

1o claims. (o1. ari-263) This invention relates to oil well drilling equip ment and particularly pertains to an automatic drill slip unit. y

In oil well drilling operations itis common practice to temporarily grip a suspended string of pipe by introducing slips into the bowl of -a rotary table and around the string of pipe so that the slips will wedge between the tapered wall of the bowl and the cylindrical surface ofthe pipe to hold the pipe. VThe simplest form of slip structure is a member which is arcuate in section having an inner arcuate face conforming substantially to the circumference of the pipe to be gripped and which face is preferably wickered to insure positive gripping action. The outer arcuate face of the slip is tapered so that it will conform to a segment of the circumference of the tapered bowl. Three or more such slips `are used as a set and due to their individual weight handles are normally applied to them so that one or two men can lift the slip to place it in position Within the bowl and to remove it therefrom. This operation is laborious and objectionable since the slips and the surface of the rotary table are often covered with drilling mud and oil. Various attempts have been made to produce a structure carrying a set of slips and acting to set the slips simultaneously within the bowl orto withdraw them therefrom. In View of the fact that ythe slips weigh considerable and that they must be arranged to encompass the suspended pipe the supporting members for the slips have been-complicated in construction and have also required the use of complicated and expensive power vlifting means. It is desirable to provide a slip structure which will carry a plurality of slip elements and will allow them to be easily mounted in position or removed therefrom by a simple manual operation, and it is the principal object of the present invention, therefore, to provide a, portable base structureadapted to be positioned near a rotary table on the derrick floor when required, and which structure carries a hanger for supporting a set of slips and being manually operable to move the slips to a set position and to withdraw them therefrom with ease.

In order that a device of the present character may serve eiectively its intended function of positioning the slip elements within arotary table, it is desirable that the slips be so carried by their supporting structure as to be rotatable relative to that structure about the axis of the table; To provide for such rotation it has heretofore been considered necessary that the supporting structure include at least one member or ring extending entirely about `the pipein use and thus re. quiring partial disassembly upon movement into andeout of an active position about the drill pipe. The resulting inconvenience in handling such slip units has caused most oil workers in practice to avoid the use of any mechanical unit of the present type and to position the slips entirely by hand. Y

A particular object of the present invention is to provide a slip supporting structure so formedA as to effectively guide the slips-for rotation while not vrequiring even partial `disassembly upon movement into and out of active position. Speciiically, I prefer to employ as supporting elements a pair of members or rings adapted to extend 'about avdrill pipe, and rotatably interconnected so that one acts as a support by which the other, carrying theslips, is rotatably mounted. To .permit movement of the unit into and out of active position without the necessity for disassembly, I form the two relatively rotatable rings to haveregistrable openings or pipe passing throats in their sides, and I interconnect the rings in a novelmanner guiding them for relative rotation without the necessity for any bearing engagement at the throat locations. As will appear, a critically important feature in providing forsuch rotary support is the employment of-unique bearing means particularly characterized by a capacity for affording bearing engagement between the rings at at least ve diierent locations spaced angularly about the rings. As a result of this capacity for ve point bearing engagement, I assure that even when the rings are not in engagement at one of the five bearing locations, by reason of the movement of one of the open throatsvto that location, there is still an eifective four f point engagement between the rings.

The present invention contemplates the provision of a base structure carrying a standard upon which a walking beam is pivoted, one end of said beam carrying a counterweight and the other end of the beam carrying a slip ring from which a plurality of slips are suspended by articulate connections. i

.'The invention is illustrated by way of examplein the accompanying drawing in which:

lFigure 1 is a view in plan showing the automatic slip unit with which the present invention is concerned.

Fig. 2 is a view in side elevation showing the automatic slip unit with its parts in their set position and indicating by dotted lines the position of the parts when in retracted position.

Fig. 3 is a view in transverse vertical section as seen on the line 3-3 of Fig. 1 and shows the composite slip supporting ring.

Fig. 4 is a fragmentary View in side elevation as seen on the line 4-4 of Fig. 2 and shows the latch lever.

Referring more particularly to the drawing, I indicates a baseplate upon Whichis mounted a vertically disposed cylindrical standard Il. This standard carries bearing rings I2 and I3 near its upper and lower ends. Telescoping over the standard I l is a vertical column I4 which is tubular and has an inner bore of a diameter 'tofpro'evide a running t with theqbearing-l rings: IZf-and I3. The column rests at its'lower end upon-ai thrust ring l which circurnscribes=-the standard` and rests upon the bearing plate ID. .Y Mounted upon the outer face of the column 'at a'point'in" the length of the area circumscribed'A by the standard Il is a pair of .l/.ugs I6 carrying a pivot pin Il. The pivot pin-lgextends horizontally and provides asupport for-.a latch lever I8. `One end of the latch-lever. is=formed withv a handle iS and the opposite end is formed with a latch dog 28. The latch dog 28 may extend through an opening 2l `in the wall of the column I4 and into an opening 22 intheewall yof the standard II. When the latch dog extends into both of said openings the column I4 `will-loe 'held against axial rotation with relation- `to the-.standard I I` andv will prevent Vthe column from being lifted clear of the standard. The upper end of the standard il Yis fitted with a handle or bail 23 by which the column and the structure assembled therewith may belifted from-the standard when desired. A horizontally vextending king pin V24 passes throughthe column I4 near itsy upperend as accommodated by `diametrically opposite openings 25 formed through the walls of the column. The king pin is provided asa pivotal connection for a walkingl beaml 2. Thewalkingebeam -2'I-ex.4 tends oppositely from the/king' pin124 togform a drill slipsupporting end 28fand alcounterweight end 29. `.As shown in Fig. 1 of the drawing, the walking beam is formed-witha pair oflcomplementary barsfill which are spaced fr orneach other-and extend along opposite-.sides kof Vthe column I4. The portions of the-bars constituting the counterweight end 29 of the walking-beam are here shown as being-parallel and-the portions of the bars forming the slip supporting portionof the walking beam'ZI are shown as rbeing spread apart for av purpose to be vhereinafter described. Thebars are disposed with their. majorwidth edgewise rand vertical and vare securedtogether by transverse brace members 3| and web plates 32 andf33. 'IheportionsA of the bars which form the end of the counterweight length ofthe walking beam are enlarged to produce a circular section-34 which agrees inV diameterwith a plural-ity of counterweight discs B. f Thesecounterweights areA interposed between if the bars 30 and vare mounted vupon a counterweight bolt 36 which passes through bores S'I-disposed concentrical-ly of 4the portions 34of the bars 38. It is obviousthat a desired number of the discs 35 are provided to counterweight the load vsupported upon the slip supporting length28 ofthe walking beam. y

y--Articulately connected with the free end-of the portion 281of`the walking beam 211is aslipsup-gporting unit 38. This unit comprises fan outer annular frame :member-:39, an inner annular Yslip supporting 'ring 4G and a plurality of slips- 4I. Ther-members 39 and 4U do not describea complete circ1e-but=are -formed'with throatsnfIZ and 4 43 which are of a width sufficient to accommodate a drill pipe 44 when the throats are in register. The annular frame member 39 is provided with a pair of arms 45 and 48 which are spaced equidistant upon opposite sides of the longitudinal center of the walking beam 2. The longitudinal center line of the walking beam intersects thevertical center of the slip supporting unit 38. The 'arms'f'45 andy 46 are formed at their outer l@ ends with transverse bores 41 and 48 through which trunnion pins 49 and 58 extend. The outer ends of therpins extend into bores I and 52 V-formed'transversely of the ends of the bars 30 V:of.the-walkingbeam*2l. The pins 49 and 5E) thus :providektrunnions;upon the axis of which the slip supportinglunit' 38 may swing vertically. It .is intended to maintain the slip supporting unit j`3S'`horizor`1tal "at allpoints in the vertical swinging-imovement of the Walking beam 21. This is accomplished automatically by equalizing links 53, -;and54.--.Theselinks arepivoted lat one end uponpivot bolts55 andlf56 which extend through the Wall of the column I4 at diametri'cally oppositefsides thereof and in the central verticalplane ofthe column. rrThe axis of-"the bolts'.- 55 and 5S is spaeedr-fromthe axis of the king pin"24 and is therebeneath. The oppositeends ofthe equalizing links 53 andP 54Y arer formed with transverse aligned bores ui'I .and 58. These .receive apivot pin 58 which extends .through transverse bores lill-and` ESI-A of lugs.B2-and'63. '.The'lugsare spaced parallel toeach other and extend from`the`s'ide of the-annularframe member' '.39 so that the horizontal axis of `the pivot `pin 59 will be .below and the same verticalplane as thefhorizontal axis of the trunnion pins 49 and'. 'These axes are spacedA apart vertically thesamedistance as the spacinggbetween-the axes of the king 'pin 24 andthe-bolts 55 and n5B. It will thus be seenthat by this'arrangement `the arm 2G ofothe walking beam -21 vand the equalizinglinksi. and'54 will have theffectfofafparallelograman'd will insuref-that-the slip -supporting unit 13'3V will be maintainedV in*l horizontal alignment at. all times. #-'Iheannu1arv frame memberg is formed with anoutery ring-shaped `portion 54 which-has an overhanging flangeil at its upper edge; Inorder torein-force theframe memben 39 a vertically extending rib-6 is` cast integral with Vthelange .and circumscribes the opening.dehnedlby'thef frame member. iAsrshown infFig.. Zof the drawings'the rib .progressively Aincreases, in height from the outer .edger of vthe :throat- 42 .to vthe arm Y45 .and then l,continues between 4the arms 45` and S to formantarcuatereinforcing rib -whi'chties-the arms-andthefoverhanging portion Yot the ringfll together. YDisposed in circumferentially spaced relation to each other-around the ring portion of'the` annular: frame member 39 are transverse 6o bores 61-which-receivecapscews .68. u.These .cap screws, -extend--intoa threaded-central boreof cylindrical rollers 69. The outerends of` the rollers-Sgare-formed with a frustoconical vportion v'I0 and-the :inner--faces--of the rollers Glare formed witha` bosse-'I Iwhich tswithin acounterborelZ in the inner face of Ythe .ring .portion 64 ofthe frame. i .1 -The rollers A69 are-provided togive'bearing` support-itorthe-annular sliygrr-ing-` 48. ..1 As-*shown in 70 Figa1i-ofethe'fdrawing,V they slip ring 48 has a ciroumscribing :channel in its.- outerY face which` providesfspaced-parallel bearing surfaces T13 and'14 agreeing substantially with the vdiameter Aof .the rollers 69. f -Ilhe -bottomof-the channel 4*has opposite tapered faces l5- and- 'lhwhich receive fthe 'inclined-faces of the frustoconical portionf1|l kof the rollers.'"-\It-will thus be seen that the annular slip ring 4|) will be supported to rotate around the central vertical axis 'of the `slip supporting unit and will be directly supported by the rollers 69. It will be further noted that due to the formation of the rollers and the contour of the channel into which they extend an anti-friction bearingis provided for. the slip ring 4|] and means are also providedto prevent lateral movement of the ring. 48 with relation to the .annular frame member 38.. The annular slip ring is designed to providea direct supportfor the drill slips 4|. These slips areof conventional design having arcuate-wickered faces 11 to engage the pipe 44 and arcuate tapered faces 18 .to engage the tapered seat 19 of a ,slip bowl 80. The bowl 88 is mounted within the turntable 88 of an oil welldrillrig.` The slips aresuspended from y slip carrying ring 48 for only rotary movement,

I find ithighlyimportant that the outer ring be adapted to guide the inner ring for its rotary movement at at least i'lve different locations spaced angularly about the rings. More specifically, there must be provided means for both supporting theinner ring and retaining it against lateral movement atthese ve locations. Consequently, it is critically important in the illustrated form of theV invention that the number of rollers 69 be at least five, as shown. As will be L appreciated, even whenone of the rollers is received within the open throatof the inner ring .and isithus temporarilyinactive thering is still adequately supported and guided byengagement with the other rollers at four different locations spacedabout more thanrl88". l

O ne of the advantages of the present invention is that the entire automatic slip structure may be pla/cedY at aproper position upon the derrick floor,V after which the column I4 and the walking beam 21 may be rotated aroundthe vertical axis of the standard II to swing the slip supporting unit 38 into or away from an embracing relation with the pipe 44. In order to accomplish thisconveniently the throats 42 and 43 of the annular frame member 38 and the slip ring '40, when in register with each other, are disposed with their center lines substantially icoincident with the arc described by the vertical axis of the slip supporting Vunit 38 as Vit swings around the vertical axis of the standard II. Thus, the walking beam may swing horizontally to place the slip support 38 in an embracing position 'with relation to the pipe or to swing it away therefrom without making it necessary to move the entire automatic slip unit with relation to the derrick floor.

The walking beam may be oscillated by connecting power applying means to lugs 85 which are secured to a cross-brace 86 disposed between the bars 3D of the walking beam and in the vcounterweight length 29.' Means, such as a fluid cylinder may be connected .to the'lugs 85 if desired.A However," in the present instance a thrust link 81 is provided.' This link connects to the Vried fromwplace to place.

lugs by a pivot bolt 88 and extends downward ly'to. connect to a lever arm 89 by a pivot bolt 90. The leverarm 89 is xed to a fulcrum shaft 9|?. This shaft .extendsnhorizontally and'is rotatably supported-iinY a bracket 92 carried upon the col` umn I4 -near its lower end. Secured to the fullcrum shaft 9| is a hand lever 93 by which the shaftlll may be rotated. As shown in Fig. 2 of the drawings the hand lever 83 and the thrust :link 81 are in position to lower the slip supportingfunit 38 toward the rotary table 80'. Attentionis directed tothe fact that the axis of the fulcrum shaft 9|is spacedsuinciently high above `the base plate I8 to permit the free end of the lever arm 89 to swing to a position beyond deadcenter when the hand lever 93 is moved in the direction ofthe arrow a, as indicated in Fig. 2, at which time the walking beam will be oscillated to lift` the slip supporting unit from the position shown in Fig. 2. It is also to be pointed out that the axis of the fulcrum shaft 9| vis spaced horizontally from the side of the column I4 a suilcent distance to allow the pivot bolt 98 to pass beneath the shaft 8| and the thrust link 81 to pass across dead-center of the shaft 8| so that the walking beam will be locked automatically with the slip supporting unit 38 in its elevated position.

In operation of the present invention the base structure comprising the base plate Il] and the standard are permanently assembled together as shown in the drawings and may be positioned at a desired .point with relation to the rotary table 88' of an oil well derrick rig. When it is desired to utilize slips in well drilling operations the entire unit comprising the column I4, the walking beam 21 and the slip supporting unit 38 may be lifted and placed over the upper end of the standard II. Of course it is to be understood that if desired the entire structure may be assembled and placed on the derrick oor as a unit, There are times however when it would be convenient to remove the walking beam and slip supporting structure so that the derrick floor would not be so crowded, in which event the column I4 may be lifted by the bail 23 and car- When the column I4 is placed in position over the standard II it is preferable that the lever 83 shall be in its dotted line position, as shown in Fig. 2. This places the pivot bolt beyond dead-center at the bottom of the column I4 and thus insures that the walking beam 21 will be supported in its uppermost position. When placing the column I4 in position over the standard II so that the standard may protrude up into the column it is desirable to rotate the walking beam 21 at substantially right angles to the vertical plane it will normally occupy when the slips are being used. At such a time the latch dog 28 will extend through the opening 2| in the column I4 and will rest against the outer surface of the standard II. The dog will be yieldably held in this position by the spring I9. At this time it will also be obvious that the throat 43 of the annular slip ring 40 will be moved to register with the throat 42 of the annular frame member 39. The slips 4I will then be hanging Yvertically from the links 8|. When it is desired to use the slips the portion 28 of the walking beam is rotated in the direction of the arrow b in Fig. 1, and if the base plate I0 and standard II have been properly set this swinging movement will cause the slip unit to swing around so that the drill pipe 44 will pass through the throats 42 and 43 of the members 7 391 andi! U respec'tively. When tha-drill: pipeahas assumedfa': position substantiallyaat fthe-center of' the gslipvsupporting `'unit ,fthezfannularl-slip supportingring 46 i may be vrotated upon `its :verideal-axis.Y `During this rotationJthe'ring-IB -Will ride .on the rollersfil. :Thus therrotation ofthe slip supporting ring mayibeV easily'accomplished. Whenthefvslip supportingring '40 has; been r0- .tatedfon Vits vertical axis until thethroatsi and 43::are .outofregister completelyfthe pipeM-will be: encircled by' the drill; slipI unit ".38. VThe .power m's'eratingf'levers- 931:?may'r then fbe swnngliins` a direction counter to thataindicated ;byv thefarrow mini-Fig. .2. v This Willlift the counterweight en'd azof the :walking :beam Land"vvillviower thefslip supporting unit soi that the slipsfll if will find-their `way downwardly' along thefftapered Avfaces 18 .of the' bowl andA will con'ietoV rest with-their. inner Wickeredfaces il' irnpingingagainstthe'circumerencenofzthe drill pipe 114. *VWhenfin this position the slips will support the pipe` Manci allow such operations to take place as are desired. -After the. slips have served vtheir useful #purpose the lever` S3 may againbe moved in the direction `ofsthe.*arrow a in Fig. 2. This Willzcausexthe. link af 81,1.ftof-swing the :counterweight tend-132 'of the 'walking bea-m'- 2'? downwardlyrand to lift thelslip supporting unit 38 free of the rotary tableff so'uthati they slips d i 'rmayswing free off the :drill 'pipe. Attention-isidirectedzto thefactf--that the bolts'fBS front,which-the slip links 8l areV suspended vare` spaced 'a greater radial distance. lfrom the vertical axis of .the'slip supporting unit 38 thanthedistance assumed by the bolts '84 at the lower `ends of I the y links f when the .slips j'are in their. set-positions." rihis insures that asV the slip nnitfis lif'tedthere will be a tendencyfor the A-links to fact automatically l fand pull the slips away frornthe pipe ed. `When. the -links f i and by rthoseg-skillediin -.=thefart, f mithoutgideparting iromithegzspirit otf-mysinventionfas; claimed.

@Having thus describedimy f inventioni :what: I

' lclaimfand` desire :to 'secure by-Lettersf'rPatentzzisz the *slips v:areyliftedV i clear -ofti1e-fbow1-V there fwill e.

be considerable fspafcer between. thecircumference'fofrthedrill string andthe inner wickerecl faces il" of-V the slips fii. Thisspace mayxprovide `suiiicient clearance to permit a drill `joint to pass downwardly through theslip supportingV unit 38 without requiring that the 'throatsr d2 :and 43 shall register and that the walking-v beamshall-'berotated on' its vertical axisv in a directioncounter tothat indicated 'by the :arrow b in-Fig. 1.

*As :has Ybeen previously'explained, power means mayibe used to raise and'lowerthe' Walking beam 2.1,:.such-for lexample .as 4bythe use-fof-anfhydraulic cylinder or other equivai'entfmeans.

ltr will thus be seen that-the'rautomatic `drill slipv unit here disclosed provides-simple `mechan- -ical means whereby a plurality ofdrillrslips lmay vbe mechanically handled'` iii-2a 'manner` to be yplaced in position within a slip bowl and around a :pipe simultaneously, aswell-as ina'manner to be: easily and quickly :removed .therefrom,-the structure being counterbalanced and; provided withmechanical'inoving means so that theentire operation of using the slips may-bei easily faccomplished by one man. It Will1also be 5seen that by the structure here disclosed'the-drillslip supporting-unit Vmay vbe easily-swung toward and away from an embracing position'with relation to thedrill pipe, andY maybe easily lifted with the associated mechanism so that' Yit t can be Yremoved from anobstructing position on "the`der rick floor. I

While I have'sh'ownthe'preferred form of" my invention as now' known *tomef it will `beunderstood thatvarious changes may be' madein combination, construction and 'arrangement 'of parts i; In .zansautomajtic :drillislipunityfan -outer- 1ar- ;cuate memberfhaving az gap-'iny a sidethereof vto admit -azrdrilh pipe' therethrough,V an inner'rarcuatedrill 'slip f support member adapted .eto' "be inserted said -o'uter 1 arcuate member, sa .plu- -rality .ofsiroliers'- removablyy mounted on; onefiof Isaidriarcuatealmembers; and :having- :rolling rotatable-support relatively toethe inneniarcuatemem- Vbeizorx:concentricrelativerrotative'movement ibetween said-:farcuatemembers,ithe`:;inner. 4'arcuate member-:having a: gap. therein :adapted vto registeriwi-thz .the gapfizin:thefouterflmember to` pass-a 4drill pipe therethrough, theI innersarcuatemember being adaptedbtofbe im'oved Arotatably rela- .tively to the i4 outer s arcuatei-mernberA ."tol. close' the gap randa-retain .aLdrill pipethereingh-andwa pluralityfof tapered 'slips suspended; fromv thelinn'e'r arcuate-member-1When:.'elevated above-aJ 1 rotary table'nwith:thezelower :edges .of saidii slips disposed radiallylinwardlyiofJ-the upper edgeo the :tapered seat when'ssoielevated to 'guideltheslips into' the seat oniloweriugl the unitzfroman Y elevated position overtheseat.

2. In a drilll-sliplunit; afsup'port memberadaptedito extend partiallyaboutlal vertically-.extend- -ingfdrlilllipipeland having-:an opening-atlone side throughiwhich' the pipef may pass upon movementof-lthel-lnemberfinto pos'ition'about the pipe, Iasliploarrying Amember adapted' to -exten'dfp'artially-:abet-the -pipe and mountedby-'the'A support :niernberl ior-rotationL-relative thereto and about thai-pipe, "saidrislip carryinglme'mber having yan openingat 'one side cadapt'ed lto pass the, pipe 'anti-.imovable into registryewith-{sa'idn opening in 'thai/support: vmember-by isaid f rotationy ofl the-slip carryingmem'ber-,ebearing means carried by one ofi said'lmembers 'and-'engageable 'With'the -other in'e'rnber-fatiat1leastfve-different locations spaced .van'gul'arly-'iabout said ione member-- tol fguide fthe slip carryingmember` for said relative rotation,

-' aliplu'ralitylot-'tapered'pipe grippingslip elements,

Y' a sliprcarryinginernber adapted to nextendpar- Artia'lly*aboutl the pipe and mountedby the support member for rotation relative thereto and about the -pipef' said Aslip carrying' member'- having `an opening at'one sideadapted'to passthe pipe and movableL into registrywith said Vopening'in` the supportmemb'er by sa'id rotation of the slip carrying'menber'j bearing v-means'.'carriedby one of 'said members and engageable; Vwith' the other member andgivingsupport tolsa'id slip carrying ing member a gap .through which the pipe may pass. l

4V4. In a drill slip unit, a support member adapted to extend partially about a vertically extending drill pipe and having an opening at one side through which the pipe may pass upon movement of the member into position about the pipe, a slip carrying member adapted to extend partially about the 'pipe and mounted by the support member for rotation relative thereto and about the pipe, said slip carryingmember having an opening atV one side adaptedV to pass the pipe and movableinto registry with said opening in the support member by said rotation of the slip carrying member, bearing means on one of said members engageable with the other member at at least ve different locations spaced angularly about said one member and acting to prevent substantial relative bodily movement of the members transversely of the axis 'of-said rotation, a plurality of tapered pipe gripping slip elements, and connecting means movably mounting said slip elements to the slip carrying member in depending relation thereto for reception in a slip bowl positioned beneath the members, said slip elements and connecting means being formed to Yprovidebetween a `pair of the slip elements while they are mounted to the slip carrying member a gap through which the pipe may pass.

5. In a drill slip unit, a support member adapted to extend partially about a vertically extending drill pipe and having an opening at one side through which the pipe may pass upon movement of the member into position abo-ut the pipe, a slip carrying member adapted to extend partially about the pipe and mounted by the support member for rotation relative thereto and about the pipe, said slip carrying member having an opening at one side adapted to pass the pipe and movable into registry with said opening in the support member by said rotation of the slip carrying member, means forming a connection between the members and including at least five rotatable bearing elements engageable with the members at as many locations spaced v thereabout and guiding the slip carrying member for said relative rotation, and a plurality of tapered pipe gripping slip elements carried by said slip carrying member.

6. In a drill slip unit, a support member adapted to extend partially about a vertically extending drill pipe and having an opening at one side through which the pipe may pass upon movement of the member into position about the pipe, a slip carrying member adapted to extend partially about the pipe and mounted by the support member for rotation relative thereto and about the pipe, said slip carrying member having an opening at one side adapted to pass the pipe and movable into registry with said opening in the support member by said rotation of the slip carrying member, one of said members having a partial annular bearing surface, at least five rollers rotatably carried by the other member and engageable with said bearing surface to give support to the slip carry'mg member at at least five different locations spaced angularly about said other member, a plurality of tapered pipe gripping slip elements, and connecting means movably mounting said slip elements to the slip carrying member in depending relation thereto for reception in a slip bowl positioned beneath the members.

7. In a drill slip unit, a rigid generally arcuate support ring adapted to extend partially about avertically extending drill pipe and having an opening'at one-side through which the pipe may pass upon movement of the ring into position about the pipe, a rigid generally arcuate slip carrying ring adaptedto extend partially about the drill pipe and mounted at the inside of said support ring for rotation relative thereto about the pipe, said Slip carrying ring having an opening at one side adapted to pass the pipe'and movablev into registry with said opening in the support ring by said. rotation of the slip .carrying ring, means forming a connection between the rings and including at least ve rotatable bearing elements engageable with the rings at as many" locations spaced thereabout and guiding the slip carrying ring, for said rotation, the angular extents of saidl openings in the sides of the ringsand the spacing of said rollers being such thatin allrelative.rotativeconditions of the rings at leastfour of Vthe rollers spaced aboutmore thanc are actively interposed between the rings, .a.plurality..of tapered pipe gripping slip elements, and connecting means movably mounting. said slip elements to the. slip carrying ring in .depending-relation thereto for receptionin a slip bowl positioned beneath the member.

8. In a drill slip .unit,.a rigid generally :arcuate supportringadapted to extend partially about'a vertically extending drill. pipe and having an opening at one side through which the pipe may pass upon movement of the ring into position about the pipe, a rigid generally arcuate slip carrying ring adapted to extend partially about the drill pipe and mounted at the inside of said support ring for rotation relative thereto about the pipe, said slip carrying ring having an opening at one side adapted to pass the pipe and movable into registry with said opening in the support ring by said rotation of the slip carrying ring, one of said rings having a partial annular bearing surface have transverse extent both vertically and horizontally, at least ve rollers carried by the other member at as many locations spaced angularly thereabout and having surfaces engaging said annular surface to both support the slip carrying ring for said rotation and to prevent substantial relative movement thereof transversely of its axis of rotation, the angular extent of said partial annular bearing surface and the spacing of said rollers being such that in all relative rotative conditions of the rings at least four of the rollers spaced about more than 180 are effectively interposed between the rings, a plurality of tapered pipe gripping slip elements, and connecting means movably mounting said slip elements to the slip carrying ring in depending relation thereto for reception in a slip bowl positioned ybeneath the rings.

9. In a drill slip unit, a rigid arcuate support ring adapted to extend horizontally partially about a vertically extending drill pipe and having an opening at one side through which the pipe may pass upon movement of the ring into position about the pipe, a rigid arcuate slip carrying ring adapted to extend horizontally partially about said drill pipe and mounted at the inside of said support ring for rotation relative thereto about the pipe, said slip carrying ring having an opening at one side adapted to pass the pipe and movable into registry with said opening in the support ring by said rotation of the slip carrying ring, said slip carrying ring having an arcuate recess in its outer surface facing the support ring, and having upper and lower roller engaging walls, said walls having outer sag-51m49- 1.1i horizontal por-tionsandinneriangularlylconverg: ingLportionsQ-tf at "least: veirolles :mountedtfsa support' ring atras many locations Levenlyspaoed angularly thereabout; ea'ohibf saidfrollers'fhavng anfouter=cy1indrica1iportion'engageabewthrsad horizontal. portions ofsaid; recessr wallsnd hav-V ing anzinner frustooonic'al portion; engageable and'fto extend about 'a `'drill pipe extendingwertife ca11y=through-the table,y a supportfto b'evn'iounih` ed atf 'a side' of''the:tab1e;.`means.V mountingsv-said member to 'ther-supportfor movement' between an active position above 1 the? center ofithel tableand a retracted positicmfoiset .tofthesidethereofgsaid member having arry opening at` one .side 2 adaptedto'pas'sthe pipe iuporr said. movement of. the ymember* between 'l 'said positions; f a secondr #member adapted to extendlbartially about. the piperzand- 12 mountedgiby:.sadirstimemberxfor rotation. rela-A tive thereto and about the pipe, said second memberzfhaving an .opening at :one sdesadapted to: pass-1 the 4pipe andy .movable into' registry with said openingninarthe frstmember upon said ro.-. tation. thereof-,f-bearing means carriedby one of saidi members." and 'iengageable Withvv the. other member Lat. atrleast. five different .locations Vspaced angularly aboutsaid. one member to .guide the second.-Lmerriberiforssaid relative rotationfa plur-` ralityoftapered 'pipe gripping slip elements, and` connectingi means mo'v'ably. mounting saidfslip. elements to'. the second'mem'ber .in fdependingsree; latio'nthereto:foreception Lin a s1ip.;bowl posi-.; tioned'beneathathexmembrs--s WALTER A.V ABEGG.

REFERENCES CITED The Ifollowingfreferences are of record in the file-:- ofA *this *patentarV UNITED-.STATES PATENTS Number Name Date 1,341;'7.021zv Blackf. Jun'e'l, 1920 1,65;864'i5 Martin-rv. Jan.`17, 1928 1,790225 Campbell .Jan.v2'i'f,` 1931 1,878,372.Y Box.: Se;ot.v20,i1932A 2,34();59.'1;k Kel-ley Feb. 1, 1944 

